4-(2-Dimethylaminoethyl)indole is disclosed by Hofmann and Troxler in French Pat. No. 1,344,579 and in Troxler et al., Helv. Chim. Acta, 51, 1616 (1968). Cannon et al. in J. Med. Chem., 24, 238-40 (1981) describe 4-(2-di-n-propylaminoethyl)indole (also named as 4-(N,N-di-n-propyl 2-aminoethyl)indole).